Cerebral venous malformation is also known as cerebral venous hemangioma and cerebral venous tumor. It is also called developmental venous anomaly because it is abnormal in appearance but still provides functional venous drainage to the corresponding tissues. Venous malformations can be divided into superficial and deep types. The superficial type refers to the deep medullary venous region that drains into the cortical veins through the superficial medullary veins; the deep type refers to the subcortical region that drains into the deep venous system. Causes Most believe that cerebral venous malformations are congenital disorders that arise from normal embryonic developmental disorders. At 45 days of gestation, the telencephalon contains a number of structures called “venous jellyfish heads,” which consist of dilated central veins and many small deep medullary veins. At 90 days of gestation, these venous structures develop into a system of superficial and deep veins. If the normal development of the veins is hindered, the early forms of venous drainage are preserved. It is also thought that partial obstruction of the developing cortical venous system causes compensatory expansion of the medullary veins. Cerebral venous malformations are often accompanied by cavernous hemangiomas or other vascular malformations, suggesting that hemodynamic changes such as increased local blood flow may precipitate venous malformations. Whether congenital or acquired, most consider cerebral venous malformations to be a normal compensatory variant of the cerebral venous system rather than a pathologic change Pathogenesis Cerebral venous malformations are primarily located in the cerebral or cerebellar hemispheres. Approximately 70% of lesions are located supratentorially, with frontal lobe lesions accounting for 40% of lesions, cerebellar hemisphere lesions for 27%, parietal or parieto-occipital lesions for 15%, and basal ganglia and thalamus for 11%. The lesions are mainly located in the subcortical white matter and can often be combined with AVMs, cavernous hemangiomas, or facial hemangiomas. Cerebral venous malformations are composed of many abnormally dilated medullary veins that converge into a central draining venous trunk of two parts with a spider-like appearance. The medullary veins mostly originate from the periventricular region, and the central draining trunk drains to the superficial cerebral venous system or to the deep subventricular venous system; the subepidural lesions mostly drain directly to the dural sinuses. The central drainage trunk is thicker than the normal veins. Microscopically, the malformed vessels are seen as veins with few smooth and elastic tissues in the walls, which may also be thickened by hyaline-like changes. There is normal brain tissue scattered between the vessels. There are no malformed arteries within the lesion, and there is rarely thrombosis, hemorrhage, or calcification. These features are clearly different from other cerebrovascular malformations, such as AVM, cavernous hemangioma and capillary dilation Most scholars believe that cerebral venous malformations are the result of abnormal changes in the normal draining veins that are congenital. The evidence supporting this view includes: (1) the disease is found in infants and children; (2) anatomically there are no other normal draining veins at the site of the tumor; (3) when the lesion is removed during surgery, the brain tissue in the corresponding drainage area is immediately bruised and swollen Imaging 1. The lesion is only visible in the venous phase. There are no signs of abnormal arteriovenous short-circuiting. The arterial phase and cerebral blood circulation time are normal. 2.CT scan is normal on plain scan. On the enhancement scan, a thick line of enhancement shadow is seen in the brain parenchyma flowing to the cortex and deep brain, without edema and mass occupancy around it. Sometimes it may also appear as a dot-like lesion. This coarse linear or dot-like shadow is the image of central venous trunk. 3.MRI scan The presentation is similar to that seen in CT. The lesion is low signal on T1-weighted image, mostly high signal on T2-weighted image, and a few are low signal. After contrast injection, the lesion shows a typical radiolucent star or spider-like Main clinical manifestations Epilepsy is the most common clinical manifestation, mainly grand mal seizures. Restricted neurological dysfunction: manifested as unilateral limb light paralysis, which may be accompanied by sensory impairment. Chronic headache. Intracranial hemorrhage: The hemorrhage rate of cerebral venous malformation is generally considered to be 15%-20%, and subcurtain lesions are more prone to hemorrhage than supratentorial lesions. The patient has sudden severe headache, coma or hemiparesis. Complications The most common complication is cavernous hemangioma. The literature reports that 20% to 30% of cavernous hemangiomas are associated with venous malformations. The histological criteria for distinguishing between the two are the presence of normal brain tissue between the diseased vessels and the size of the vascular lumen. Cerebral venous malformations can also be associated with other vascular or nonvascular lesions, such as tumors, demyelinating diseases, aneurysms, AVMs, dural arteriovenous fistulas, smoker’s disease, and vascular lesions of the head, face, and eyes. Treatment For cerebral venous malformations with epilepsy, antiepileptic treatment is given with good results, while others can be given general symptomatic treatment. In case of hemorrhage, cranial hematoma removal or intracerebroventricular hematoma removal and drainage can be done, and the patient can mostly recover well after surgery. The treatment of cerebral venous malformation should be cautious, because the chance of rebleeding after surgery is low, and the resection of the lesion immediately causes venous infarction of brain tissue, resulting in brain tissue swelling, bruising, and even brain necrosis, so generally only the removal of hematoma, cerebral venous malformation is not clamped or resected. Cerebral venous malformations do not respond well to gamma-knife radiotherapy, and the disappearance rate of lesions after treatment is very low and can cause radioactive brain damage.